Sheet detector control mechanism for printing presses



Jan. 30, 1951 w. w. DAVIDSON 2,539,382

SHEET DETECTOR CONTROL MECHANISM FOR PRINTING PRESSES Original Filed Aug. 11, 1941 6 Sheets-Sheet 1 INVENTOR.

Will/0171, ilafld Baud/5 0/2 BY MM W Jan. 30, 1951 w. w. DAVIDSON SHEET DETECTOR com'xor. MECHANISM FOR PRINTING PRESSES 6 Sheets-Sheet 2 Original Filed Aug. 11, 1941 INVENTOR. WJZZZO/R Wand flaw'asa/z Jan. 30, 1951 w; DAVlDSON SHEET DETEC OR CONTROL MECHANISM FOR PRINTING PRESSES 6 Sheets--$h96t 3 Original Filed Aug. 11, 1941 Jan. 30, 1951 w. w. DAVIDSON 2,539,382

SHEET DETECTOR (JONTROL MECHANISM FOR PRINTING PRESSES Original Filed Aug. 11, 1941 6 Sheets-Sheet 4 I N VENTOR.

BY mam-imam Jan. 30, 1951 w. w. DAVIDSON SHEET DETECTOR CONTROL MECHANISM FOR PRINTING PRESSES 6 Sheets-Sheet 6 Original Filed Aug. 11, 1941 Patented Jan. 30, 1951 SHEET DETECTOR CONTROL MECHANISM FOR PRINTING PRESSES William Ward Davidson, Evanston, Ill., assignor,

by mesne assignments, to Davidson Corporation, a corporation of Illinois Original application August 11,1941, Serial No. 406,328. Divided and this application January 22, 1945, Serial No. 573,840

Claims. 1

The subject matter of this invention is a twopurpose duplicator capable of doing both direct and offset printing. For direct printing, the raised type, or so called letterpress" process, is ordinarily used; and for offset printing, the lithographic process is preferred.

Most, if not all, duplicators on the market before this invention were one-purpose machines. They could do either letterpress printing, directly from a raised type plate to the sheet being printed, or they could do offset lithographic work in which the positive image on the lithographic plate is first transferred to a rubber blanket and then to the sheet being printed. They cannot, however, do both direct and offset printing.

The offset lithographic process is rapidly displacing direct letterpress printing for reasons unimportant here, but there are some printing jobs which, by reason of inherent limitations in the lithographic process, or because of cost, are almost necessarily performed by th letterpress process.

nd. the like is one such instance. This is called imprinting.

Large printing shops can afford to have both lithographic presses and letterpress machines, but there is a large demand in smaller printing establishments, and in stores, manufacturing plants, business houses, and the like, for a single, relatively small, moderately priced duplicator capable of doing quality printing by either the letterpress or lithographic processes.

A two-purpose duplicator designed for and used largely in this specialized field, will, in most instanc s, be operated by persons skilled only slightly, if at all, in the printing field, and hence one of the paramount objects of the invention is to so organize, construct, and arrange the essential elements and mechanisms of the machine that it is characterized by simplicity, ease of adjustment, convenience of operation, and the speed by which it can be converted from a direct printing letterpress machine to an offset lithographic machine, and vice versa.

To achive the broad objects of a two-purpose machine, theconventional employment of three printing cylinders is discarded, and, instiad, only two cylinders are used, one being larger than the other and preferably having a diameter that Printing just a few words in a blank left inpreviously printed pamphlets, cartons,

is twice that of the smaller cylinder. The larger cylinder or drum is provided with removable plate and platen segments, while the smaller drum carries a blanket. When the machine is used for lithographic offset printing, a plate is mounted on the plate segment, and during onehalf the revolution of the large drum the image is transferred to the blanket, and during the next half revolution of the large drum the blanket transfers the image to the sheet being printed.

To convert the machine into a direct printing letterpress duplicator, the platen segment is removed, and in its place a direct printing letterpress se ment is substituted. The plate segment is removed from the machine and, if a hard platen surface is required, it may be substituted for the blanket, or a steel cylinder may be substituted for the blanket cylinder. The dampening mechanism used when the machine is doing lithographic printing is constructed so that it is self-contained and may be removed from the machine with little efiort. The entire conversion from lithographic printing to letterpress printing can be accomplished within the spac of a very few minutes.

The throwout mechanism for automatically separating the printing cylinders whenever a sheet fails to reach the bite at the prescribed time is a novel feature of this invention. It is so constructed that it is quiet in operation and is characterized byits relative simplicity.

In the drawings:

Figs. 1A and 1B are diagrammatic views of the press and conveyor table, respectively, arranged for oifset lithographic printing.

Figs. 10 and ID are diagrammatic views of the press and conveyor table, respectively, arranged for direct letterpress printing.

Fig. 2A is a fragmentary perspective view of the preferred form of the press.

Fig. 2B is an exploded perspective ,view showing the sheet detector and counter actuator. In assembly, the sleeve I30 is carried by shaft I52.

Fig. 3A is a transverse generally vertical sec tion taken approximately on the line 3A3A of Fig. 1A.

Fig 4A is a longitudinal vertical sectional view taken approximately on the line 4A4A of Fig. 3A.

Fig. 5A is another vertical longitudinal secacaaaaa tional view, taken approximately on the line Y A-5A of. Fig. 3A and showing diagramatically, in a broken-away portion thereof, the feeder which is controlled through the controls shown in the main portion of the figure.

Fig. 5B is a fragmentary view showing the cutout position for ducking apparatus of the ink ductor roll.

Fig. 6A is a fragmentary detail view illustrating the platen throwout and counter mechanisms; and

Fig. 6B is a view illustrating the independence of the feeler from the counter when no sheetis present.

At the outset, it should be understood that the invention may be embodied inmany forms, but a preferred embodiment has been illustrated in the drawings and will hereinafter be described in detail.

Before considering the detailed structure of the machine, it will be helpful to refer, first, to the diagrammatic illustrations shown in Figs. 1A to 1D. 1

In Fig. 1A, the machine is shown set up for offset lithographic work, and in Fig. 1C the machine is shown set up for direct letterpress work. By considering the progress of a sheet of paper through each arrangement of the press and the timed relationship of the various parts of the machine as they cooperate in applying the image to the sheet, it will be easier to understand the detailed description that follows.

GENERAL ORGANIZATION A. Lithographic oflset printing (Fig; 1A)

Sheet A in Fig. 1A has just been printed, and sheet B is about to be lifted by the suction head of a feeder C, an intermediate sheet already being on a diagonal tape conveyor board D. Upon reaching the rotatable stop fingers E, sheet B may be jogged against a side guide, against which it is also urged by the diagonal tape, to assure proper lateral position. At the same time, or shortly thereafter, a feeler finger F is moved toward the bite of the printing rolls to check that the sheet is in proper position. If for any reason the sheet is not there, the finger F will drop through a slot in the feed board and actuate an arm G, which functions to separate the printing rolls; but, if a sheet is present, it prevents the feeler finger F from dropping into the slot and the printing rolls are held in cooperative relationship. The same movement of the feeler finger F also operates a counter if a sheet is present. Otherwise, the counter is not actuated.

After the sheet has been brought into end registry with the stop fingers E and has been properly positioned laterally, as the feeler finger F makes its check, the upper of feed rolls H descends upon the sheet, grips it while the rolls are still stationary, and then cooperates with the lower feed roll to move the sheet toward the bite of the cylinders while the stop finger E is rotated out of the way.

During this process of bringing sheet B to the bite of the printing cylinders, the upper or larger cylinder I, which carries a plate J on one peripheral segment and a platen surface on another peripheral segment K, has been rotating to ink up the plate J, and apply the image to the blanket L carried on the smaller or lower cylinder M, where it is ready to be applied to the sheet when it reaches the bite of the printing cylinders. As will be seen by reference to Fig. 1A, the water form roller 216 of the dampening unit around the blanket drum M to a position where it is again opened by a cam T to receive sheet B as it is fed forwardly toward the bite of the cylinders. The gripper Q then closes and grips the sheet to carry it through the bite, while the feed rollers H, which have been traveling at a peripheral speed slightly above the peripheral speed of the printing cylinders in order to insure proper registration of the sheet within the gripper Q, releases the sheet and the gripper carries the sheet through the bite and thence around the drum-like assembly S, where it is released into the catcher.

' A suitable cam is provided along the margin of the platen segment K to lift the water form roller and the ink form rollers from the platen when it passes beneath these rollers, and it should be noted that during the period that the platen K is passing under the inking mechanism O the rollers of this mechanism are continually rotating to break up the ink and replenish the ink on the ink form rollers for the next application of ink to the printing plate.

B. Letterpress printing (Fig. 16') would be replaced by a direct printing element which in the illustrated form shown in Fig. 1C is a type-bearing segment U. It will be observed that this is put in the position of the platen rather than in the position of the plate so that it will co-act with the smaller lower cylinder at the time a sheet is fed thereto. In this instance the lower cylinder serves as a platen. In some instances its blanket may be used as a platen surface and in other instances it may be desirable to remove it and apply a harder surface.

When a typographic printing member, such as type segment U is used, no dampening is necessary and hence the dampening unit N of Fig. 1A may be omitted. The plate J will also be omitted and, if the segment bearing it is not also removed, the ink form rollers will be completely out of contact with this segment but will be allowed to come into contact with the type on the type segment U, which will then print directly on the upper surface of the sheet.

Since the upper surface of the sheet is printed, it is desirable to deliver the sheet to the collector P without turning it over, so that the sheet may be inspected. To this end a special cam V is provided, as seen in Fig. 10, which opens the gripper Q approximately at the position thereof shown in Fig. 1C or shortly before reaching this position. An ejector roller W is provided to cooperate with the drum-like wheels S to insure continued movement of the sheet A so that it is delivered into the collecting box P or other suitable receiver. Of course, the collecting box P may be the same collecting b0)? as that shown at P in Fig. 1A moved to a new position.

A modified form of the press for direct printing should alsov be mentioned. According to this I sheet of paper for each plate. Thus, the blanket L would serve only as a platen or could be replaced by a platen. A second gripping unit would be provided in the chain delivery unit midway of the length of the chains from the gripping unit Q. The cams at the margins of the plates would cause both plates to be inked and, if they were lithographic plates, to be dampened before inking. As each plate approached the platen roll M, a sheet would be fed to one of the grippers and carried by it to the bite where it would be printed by said plate. The sheets could be delivered to the same receptacle or to two different receptacles.

C. Combined ofi'set and direct printing, front and back With the form of the press illustrated, both the front and the back faces of a sheet could be printed simultaneously by a special arrangement. For this purpose the ofiset plate J would be left in place and the platen segment K would be replaced by a segment bearing a direct-printing lithographic plate. The plate J would be a positive plate so that it would produce a negative image on the blanket L, which in turn would print a positive image on the underface of the sheet. The plate in place of the segment K would have a negative image thereon so that it would print a positive image on the upper face of the sheet at the same time that the blanket prints the lower face thereof. Thus, the negative plate in place of the platen K would serve as the platen for the blanket L, while the blanket would simultaneously serve as the platen for the negative plate. It should be observed that no change is necessary in the feeding or delivery for this arrangement. Of course, the dampening and inking form rollers would be permitted to contact both plates.

DETAILED DESCRIPTION From the foregoing description of the general organization of the press, it is believed that the general operation of the press will be sufliciently clear so that a detailed description of the various parts may be readily understood.

PARTS B TO D-PRELIMINARY FEEDING The sheets may be separated from one another by any desirable sheet separator. That which is partially illustrated is a, suction feeder of a type which has been manufactured heretofore by the Davidson Manufacturing Corporation. The sheets are lifted up one by one by a suction nozzle II and fed to pull-out rolls if, the lower of which is constantly driven and the upper of which is accurately positioned with respect to the lower roll by thumb nut iii. A detector may be provided for automatically deflecting the sheets from their normal course if more than one is fed at a time.

The entire sheet-separating unit C is controlled by linkage l6 driven from a crank pin II rotating rigidly with printing cylinder I so as to ensure accurate timing of the preliminary feed of the sheets with respect to the movement of the press. In the form of feeder illustrated.

6 the feeder includes pile mechanism for automatically raising the pile of sheets B so that the top sheet thereof will always be at a level suitable for engagement by the nozzle II.

The pull-out rolls l2 pass the sheet on to a conveyor table D which may comprise a belt or belts 2| and one or more preliminary rolls 2!. Suitable traction means, such as marbles 23, may be provided for pressing the sheet against the rolls and the belt.

Reversible bias For various reasons it is sometimes highly desirable to position a sheet by two particular edges, say the top edge of the sheet and the righthand edge of the printed side of the sheet. If the upper face of the sheet is being printed,- the positioning of a side guide 28 at the righthand side of the conveyor table D will be correct and the sheet may be pressed against this side guide either by biasing (slanting) the tapes toward the side guide or by providing a jogger for engaging the far side of the sheet to press the sheet against the side guide, or both. However, it will be observed that if the underface of the sheet is being printed, the edge of the sheet which is the right-hand edge of the top face of the sheet is the left-hand edge of the bottom face of the sheet and would be the left-hand edge of the printed sheet. Accordingly, in order to permit lateral registration by the right-hand edge of the underface of the sheet, it is preferred that the side registration means be reversible. To this end the table D may have incorporated therein the reversible bias features disclosed in my Patent No. 2,190,413, the tape carrying and driving rolls 2! being shiftable about approximately vertical axes along the iongitudinal center line of the table, and the belts being shiftable thereon so as to bias the sheet. either to the right as shown in Fig. 1B or to the left as shown in Fig. 1D. The side guide 26 is preferably interchangeable between the two sides of the machine.

Instead of relying on a biased conveyor table D, a j ger may be used for pressing against one side edge of the sheet, preferably pressing ,it against a side guide on the other side of the sheet. If it is desired to have the jogger optionally eifective in either direction, this may be accomplishd by having a single jogger reversible on a rod and providing means for changing the timing of the reciprocation of the rod so that at the proper time it can be made to jog the sheet in either direction. Of course, the side guide could be shiftable to either side as in the case of the side guide 28 of Figs. 13 and 1D. 01' course, a press may have both reversible bias and reversible jogging.

PARTS E TO H-FINAL FEEDING The parts E to H and their control may be substantially the same as those illustrated in my prior Patent No. 2,246,508. Preferably they are all controlled by cams rotating rigidly with one of the printin rolls so that utmost accuracy of timing is ensured. As best seen in Fig. 4A, the pressure roll 30 (of feed rolls H) is raised by cam 3| operating through lever 32, an angle bar 33, which may be considered as a shaft, being pivoted at 35. The angular position of the cam ll with respect to the other control parts is such that while the pressure roll 30 is raised, a sheet will be fed under it against stop fingers E. The stop fingers E are carried by shaft 34 which also has feed roller 36 rigid thereon, as seen best in Fig. 2A.

The shaft 34 and with it the stop fingers E and the feed roller 38 are jointly driven as seen best in Fig. 5A. The shaft 34 carries a pinion 31 which is driven by a gear segment 38 carried by a pivoted lever 39, the follower roller 40 of which is urged against cam 4| by spring 42 compressed along slide rod 43.

As cam 4| rotates, it will swing lever 38 and gear segment 38 downwardly, rotating stop fingers E and feed roller 36 in an advancing direction. The shape of the cam 4| is such as to accelerate the sheet smoothly and rapidly so that, before the grippers Q close upon the sheet, the sheet will have reached a speed slightly in excess of the speed of the grippers Q so that the sheet will be buckled slightly against the registration stops of the grippers Q.

After the grippers have closed on the sheet, the cam 3| raises. pressure roller 30 so that the sheet may be drawn freely by the grippers. After raising of the pressure roller 30, cam 4| rotates to a point where it permits spring 42 to push the gear segment 38 upwardly, rotating the stop fingers E and feed roller 36 back to the starting position intime for the next sheet to be fed against the stop fingers E.

PARTS I TO K- LARGE CYLINDER The construction of the large cylinder I is probably seen best in Fig. 3A. The end walls of the cylinder are formed by discs 46 which are rigidly mounted on a shaft 41 journaled (with ball bearings) in the press frame. Platen K and plate holder 48 for plate J comprise segments which are suitably secured to the discs 46 spanning the space between them, and are provided with suitable stiffening ribs, as clearly shown in the drawings.

The preferred securing means for the segments comprises as best shown in Fig. 3A a socket screw 5| countersunk into the plate holder 48 passes through a slot 52 in the rim 53 of each disc 46 and screws into a nut 54. The nut is especially shaped to conform to the inner face of rim 53 and is elongated so that it can easily be prevented from turning by engagement with a shoulder 55 at the side thereof. -A plate 56 is preferably secured to the rim 53 and provided with a flange 51 to retain the nut in place before the screw 5| is screwed into it, or while the plate holder 48 and the screw 5| are removed. A pin 58 is provided in the nut 54 to facilitate shifting the nut circumferentially along the rim 53 to position it for alinement with the screw 5| as the latter is about to be inserted.

The elongated slot 52 permits shifting the plate holder 48 with the plate thereon circumferentially of the discs 46 for the purpose of adjusting the head margin on the sheet being printed. It is merely necessary to loosen the two screws 5|, one for each disc 46, and the segment 48 may be slid the length of the slot 52. When the segment 48 has been moved to its new position so that the head margin on the printed sheet will be correct, the two screws 5| are again tightened and the segment 48 is firmly in place.

The platen K may, if desired, be mounted so that a type-holding plate may readily be substituted for the platen.

Segment lock In order to facilitate adjusting the segment 48 (or the type segment) for head margin adjustmeat, a lock arm 63 (Fig. 4A) is pivoted to a bracket 64 carried by crossbar 358 of the main frame and is provided with a pin 65, which, as shown in dotted lines in Fig. 4A, may be inserted in a hole 66 provided in segment 48 for the purpose. With the lock pin 65 thus in place, the segment is held against turning so that the head margin adjustment may be made simply by turning one of a pair of handles 61, one of which is shown in Fig. 2A, which turn the press. The handles 51 are rigidly mounted on a shaft 68 on which is also rigidly mounted a pinion 68, best shown in Fig. 5A which meshes with lower cylinder gear 1|.

It may be noted, incidentally, that the shaft 68 is part of the main drive for the press, being driven, as shown in Fig. 10, by motor driven belt 12 which extends along pulley 13 on shaft 68.

PARTS 1. TO MSMALL CYLINDER As seen in Fig. 3A, the small lower cylinder M may be cast in one piece, that is, with its peripheral portion 86, end portions 8'| and hub flanges 88 integral. The hubs 88 may be provided with bearing sleeves 88, which run on hearing portions 8| of a shaft 82. The shaft 82 may be provided with trunnions 83 and 84 eccentric to the bearing portions 8|, and journaled in bushings 86 and 81, which are rigidly secured to the main frame except for adjustability of bushing 86, described hereinafter.

As will be evident from Fig. 6A, a slight rotation of the shaft 82 about the axis of trunnions 83 and 84 will shift the cylinder M toward or from the upper cylinder I. The shaft 82 is held at a given angular position by a collar 88 rigid therewith, and seen best in Fig. 3A, which in turn is normally rigidly secured to latch disc 88, which in turn normally bears against pivoted latch arm |0| (Fig. 6A), which is normally held in latching position by means described below.

Pressure adjustment inders I and M, may therefore be adjusted by shifting collar 88 with respect to latch disc 88. This may be accomplished manually after loosening screws I83, which normally hold them locked together. It is preferred that a screw |04 be provided for facilitating a micrometric adjustment between the latch disc 88 and the collar 88 for determining the pressure of the plate J on the blanket L with utmost accuracy.

Uniformity of pressure along the line of contact may be obtained'by loosening screw I06 (Fig. 3A) and turning bushing 86. Screw I06 passes through a slot in the flange of bushing 86. The bore in 86, in which the trunnion 93 is journaled. is eccentric with the outer surface of the bushing 86, so that rotation of the bushing88 will move one end of the shaft 82 toward or from the large cylinder I, thus producing a uniform pressure irrespective of manufacturing variations.

AUTOMATIC CYLINDER THROWOUT When a sheet approaches the stop fingers E it slides on top of a table I (Figs. 2A and 6A) comprising a sheet of metal. This table is provided with a cut-out slot ||2. A detector or feeler H3 is reciprocated along this slot, and is pivotally mounted and so weighted that its leading end 4 will drop into the slot if no sheet is 9 present, but will be supported by the sheet if one ispresent.

If no sheet is present and the reciprocating feeler II3 drops into the slot II2, it will, upon its movement in the direction of the moving sheet, engage and actuate an arm II3 mounted on a shaft H1. The shaft H1 is normally urged by a spring II9 toward the position shown in Figs. 2A and 6A, with arm I I9 resting against cross bar II9. When actuated by the feeler II3 the shaft turns a pin I2I thereon to the right (counterclockwise), thus putting tension on spring I22 to urge the latch arm IIII downwardly. Normally spring I I3, in urging shaft I I1 to its normal position, acts through it to urge pin I2I against shoulder I23 of fitting I24 by which latch arm IIII is carried, thus urging the latch arm into the engaging position shown inFigs. 2A and 6A. The fitting I24 is pivotally carried by a fixed sleeve I23, which also forms a bearing for shaft H1. The sleeve I26 is carried by the main frame and is provided with a slot I21 for receiving the pin III. The pin I2I in turn holds the fitting I24 on the sleeve I 26.

It is evident that the feeler I I3 must be driven in synchronism with the press, and with such timing with respect thereto that the feeler III will be reciprocated in its feelin direction, forwardly of the direction of sheet movement, while a sheet, if properly fed, is present over the slot I I2. Tothis end the feeler is preferably actuated by a cam on the main cylinder I, and it has been found most convenient to connect it to lever 32 by a link I29 pivoted to lever 32, and adjustably positioned in an eye I28 which is pivoted to a short arm I29 rigid with arm I29. As seen best in Fig. 2B, the arms I29 and I29 are both rigidly mounted on a sleeve I39. The sleeve I30 pivots freely on shaft I52 carried b the main frame. This control of the feeler through lever 32 has the incidental advantages that the feeler H3 is moved forwardly at a time when it will aid in ensuring iirm contact of the sheet against the stop fingers E as the pressure roll 39 is lowered onto the sheet, and the feeler H3 is not moved rearwardly until the sheet has already been gripped by the grippers of the chain delivery so that proper registration is ensured.

The instant when the feeler detects the absence of a sheet at the slot I I2 is not the proper time for a throwout or the separation of the cylinders, since at this instant the cylinders may still be printing the preceding sheet. Release at the time of detection is prevented by the pressure of latch shoulder I3I on latch arm II, this pressure resulting from the tension of sprin I32 on lever I33 which is pivoted to the main frame at I34. Lever I 33 is connected to latch disc 99 by an adjustable link I33.

Just before the proper instant for a throwout movement, a cam I31 on shaft 41 of the large cylinder I acts on cam roller I38 to pivot lever I33 counter-clockwise, as seen in Fig. 6A, and relieves the pressure of latch shoulder I3I on latch arm IIII. If the throwout shaft II1 was actuated as a result of the absence of a sheet, the spring I22 will now draw the latch arm down out of its position for engaging the shoulder I3I. At this time the reducing portion I 39 of cam I31 will reach the cam roller I33 and release the lever I33, so that it will'be drawn clockwise by spring I32, thus shifting latch disc 99 in a counterclockwise direction, and with it the shaft 92. R0- tating the shaft 92 in a counter-clockwise direction about its trunnions 93 and 94 will thus cause 10 the lower cylinder M to drop away from the upper cylinder I so that, as the cylinders continue to rotate, there will be no contact between them, and

hence no oflsetting of ink from the blanket on the cylinder M to the platen on the cylinder I.

The throwout occurs shortly before the platen on cylinder I reaches the line of contact with cylinder M, and, after the platen has passed this line of contact, cam I31 will again act upon cam roller I33 to actuate lever I33, link I33, and latch disc 93 to turn shaft 92 in a clockwise direction to restore cylinder M to its printing position. If in the meantime a sheet has been supplied at the proper time for the ensuing impression, the feeler I I3 will have been held out of the slot H2 and the spring I22 will no longer be holding the latch arm IIII down. Instead, the spring II9, acting through shaft H1 and pin I2I, will be urging the latch arm IIII upwardly, and as soon as the latch disc 99 has been turned by cam I31 to a latching position the latch IIII will slip up behind the latching shoulder I3I, thus holding the parts in the printing position even when the reducing portion I39 of cam I31 would otherwise allow them to shift again to the throwout position.

Silent stop it will be observed that each time a sheet is missing, spring I32 will cause a sudden movement of lever I33 in a clockwise direction, as the steeply reducing portion I39 of cam I 31 passes under roller I33. In inking up the press without starting the sheets, or in like situations, this sudden shifting of lever I33 each revolution would result in a noisy press unless th lever I33 were stopped quietly. According to the present invention a substantially silent stop has been provided, the nature of which is seen best in Fig. 6A.

.A stop roller I is rotatably carried by a pin I42, which is secured to link I 43, pivoted at I44 to the main frame. Spring I48 urges the link I43 in a counter-clockwise direction, pressing the roller I4I against lever I33. When the high portion of cam I31 suddenly rides out from under the follower roller I38, the lever I33 does not strike a rigid stop but. instead, shifts the stop roller I4I, with which it is already in contact, to the left or in a clockwise direction, thus pivoting the link I43 about its axis at I44. The link I43 is of such length that lever I33 is limitedto its proper movement and the cam roller 33 does not strike against low point of cam I31. It will be observed that the lever I33 is stopped without having any moving parts strike a fixed part.

Hence the throwout operation of the press will It is customary to provide a counter I 5| for counting the sheets printed. Counter I5! herein shown is actuated by shaft I52 operating through linkage I53 and spring I54. A return spring, in the counter or elsewhere. urges the parts to the position shown in full lines in Fig. 2A and in dotted lines in Fig. 6A, the return movement being limited by stop screw I6l. The shaft I52 is actuated from this position by a crank arm I59. The weight or torque of linkage I53 overbalances that of arm I56 and aids the return spring in urging the return of the parts.

It is very desirable that the counter count only actual sheets printed, and revolutions of the press. This is accomplished in the present invention by having the crank arm I53 actuated by the feeler I I3, but actuated by it only when a sheet is present. As shown in Figs. 2A and 6A, feeler H3 is provided with an arm I51, which has a dog I58 at its end. This dog is positioned, when a sheet is present, to strike a dog I'59 at the bottom of crank arm I56. In short, when a sheet is present the reciprocation of feeler H3 causes dog I58 to engage dog I59 and turn crank arm I56 and shaft I52 to operate the counter I5I through linkage I53.

When there is no sheet present the feeler H3 pivots so as to fall into slot II2, and this pivotal movement raises dog I58 so that it passes over dog I59, as shown in Fig. 6B, and thereby avoids actuating the counter mechanism.

From Fig. 6A it will be seen that dogs I58 and I59 have their engaging faces inclined at such an angle that once they have come into engagement the feeler II3 can no longer pivot under influence of its weight with respect to lever I29. The result is that as the lever I29 swings to the position shown in full lines in Fig. 6A, it will raise the feeler II3 to the position in which it is shown in full lines in the same figure. This is advantageous, since it raises the feeler II3 off of the sheet before the forward movement of the feeler H3 ceases, thereby preventing any dragging of the feeler II3 on the sheet. Because of the inclination of the faces of dogs I58 and I59, the dog I59 must come to rest sufficiently far forward of the corresponding resting position of dog I58 so that the feeler II3 may pivot freely as it feels for the presence of a sheet.

It will usually be preferred to have the feeler II3 come to rest on top of the table II I just to the right of slot II2 (Fig. 6A), so that as a sheet passes under it it will merely have to tip the feeler by the thickness of the sheet. Accordingly, it is necessary for the dogs to be sufficiently separated so that the feeler I I3 can move to the position of slot I I2 and still be free to pivot. The position of dog I58 is determined by the adjustment of the nuts on the threaded link I28, the position of link I28 at the time in question being determined by the shape of the cam 3|. The position of the dog I59 may be determined, as best seen in Fig. 2A. by adjusting a stop screw IIiI in a bracket I62 mounted on the main frame. The stop screw I 6| may be engaged by any convenient member of the linkage I53, under influence of the return spring.

CAMS

Referring to Fig. 3A, the cam at the extreme right-hand side of the figure is the earn 131, seen also in Figs. 6A and 2A. This is the cam that operates lever I33 to bring the cylinders into printing relationship after a throwout. By loosening screws 366 which secure it to a collar 36! fixed on shaft 41, the cam may easily be adjusted so that it will hold the cylinders positioned in printing relationship only while the gap 368, as shown in Fig. 6A, between the plate and the platen is at the position of contact between cylinders I and M. This timing of the bringing together of the cylinders I and M is very advantageous because. when a sheet is skipped the plate does not again apply ink to the blanket, and hence the next sheet printed will be printed with the same high quality as if one had not been skipped. Furthermore, in inking up before the sheets are fed, the press may be run as long as may be-desired without over-inking the blanket. Of course, this timing can be obtained without adjustability.

Looking from right to left in Fig. 3A, the control member next after the cam I31 is sprocket 258 which, as described in myapplication, Serial No. 406,328, filed August 11, 1941, now issued as Patent No. 2,387,750, under date of October 30, 1945, and of which=this application is a division, controls the inking unit in accurately timed relationship to the cylinders I and M.

Again, following from right to left in Fig. 3A, the next cam is the cam 3I which controls the pressure roller 30 and the feeler II3 so as to bring the pressure roller down on the sheet while the sheet is stationary in contact with the stop fingers E, the initial movement being accompanied by a forward movement of the feeler M3, which will aid in making sure the sheet is firmly against the stop fingers E.

The next control element to the left of cam 3i is cam 22?, carried by the platen to lift the dampening and inking form rollers so that they will not engage the platen, as described in detail in my last referred to patent. A similar cam 221 is carried at the other side of the platen.

Immediately to the left of the last-mentioned cam 221 in Fig. 3A is ring gear I96, which is the main drive gear for the upper cylinder I, being driven by the lower cylinder gear II which in turn is driven by pinion 69 on shaft 68, as previously described. It may be noted that the lower cylinder gear 1I rotates about a fixed axis. viz: the axis of the outer surface of bushing 96, and is connected to the lower cylinder M through any suitable form of Oldham coupling 31 I. This coupling maintains constant angular relationship between the gear II and cylinder M, in spite of relative movement between their axes resulting from the throw-out or pressure adjusting movements of the eccentric shaft 92.

To the left of the ring gear I96 in Fig. 3A is cam 4|, which drives lever 39 and its gear segment 38. This cam is positioned, and may be adjustably positioned, to start moving the feed roller 36 and the stop finger E immediately after the pressure roller 30 has been lowered thereon. It may be noted that the shape of the cam is such as to accelerate the sheet smoothly, thrust it into the open gripper Q, and over-feed it sufficiently to slightly buckle the sheet so that it will be pressed reliably against the registration stop fingers 322 of the gripper Q.

At the extreme left end of the shaft 41 in Fig. 3A is a collar 313, which drives the linkage I6 for controlling the primary sheet feeder C to feed sheets at the properly timed relationship with the press.

CLAMPS Any conventional or suitable clamps may be used for the plate, the blanket and the platen sheets. In each instance a clamp or securing means may be used which best meets the needs of the particular situation.

While I have shown what I consider to be a preferred embodiment of my invention, it will be understood that various modifications and rearrangements may be made therein without departing from the spirit and scope of my invention.

The present application is a division of my earlier application, above referred to, Serial No. 406,328, filed August 11, 1941, now issued as Patent No. 2,387,750, under date of October 30, 1945.

I claim as my invention:

1. A printing press including a printing couple comprising a pair of printing cylinders one of other into and out of printing relation with the latter, latch disc means associated with said one cylinder, a latch member engageable with said latch disc means, first spring means for said latch member for normally disposing the latter in an operative position to be engaged by said latch disc means, second spring means for urging said latch disc means in a direction to move said one cylinder away from said other cylinder and engaging said latch disc means with said latch member in the normal operative position of the latter to hold said one cylinder in printing relation with said other cylinder, cam means for said latch disc means for relieving the latter from said latch member against the force of said second spring means, means associated with said latch member for rendering said first spring means inoperative and for disposing said latch member in an inoperative position free of said latch disc means. and sheet detector means including a feeler finger operable in the absence of a sheet thereat to engage said last named means in timed relation with operation of said cam means to engage said last named means and render said first spring means inoperative.

2. In a printing press including a printing couple comprising a pair of printing cylinders one of which is movable toward and away from the other thereof into and out of printing relation with the latter, latch disc means associated with said one cylinder, a latch member engageable with said latch disc means, first spring means for said latch member for normally disposing the latter in an operative position to be engaged by said latch disc means, second spring means for urging said latch disc means in a direction to move said one cylinder away from said other cylinder and for engaging said latch disc means with said latch member in the normal operative position of the latter to hold said one cylinder in printing relation with said other cylinder, cam means for said latch disc means for relieving the latter from said latch member against the force of said second spring means, third spring means for said latch member, trip means for said third spring means for loading the latter to overcome the force of said first spring means to dispose said latch member in an inoperative position free of said latch disc means, and sheet detector means including a feeler finger operable in the absence of a sheet thereat to. engage said trip means to load said third spring means to dispose said latch member to its inoperative position in timed relation with actuation of said cam means relieving said latch disc means from said latch member.

3. In a printing press including a printing couple comprising a pair of printing cylinders one of which is movable toward and away from the other thereof into and out of printing rela-- tion with the latter, latch disc means associated with said one cylinder, a latch member engage able with said latch disc means, first spring means for said latch member for normally disposing the latter in an operative position to be engaged by said latch disc means, second spring means for urging said latch disc means in a direction to move said one cylinder away from said other cylinder and for engaging said latch disc means with said latch member in the normal operative position of the latter to hold said one cylinder in printing relation with said other cylinder, cam means for said latch disc means for relieving the latter from said latch member against the force of said second spring means, third spring means for said latch member, a table for feeding sheets to be printed to said second printing couple having an opening therein, trip means for said third spring means extending downwardly from the opening in said table operable for loading said third spring means to overcome the force of said first spring means to dispose said latch member in an inoperative position free of said latch disc means, and sheet detector means including a feeler finger disposed above said table and operable in the absence of a sheet thereon to project through said opening and engage said trip means to load said third spring means and dispose said latch member to inoperative position in timed relation with actuation of said cam means relieving said latch disc means from said latch member.

4. A printing press incl'zding a printing couple comprising a pair of printing cylinders one of which is movable toward and away from the other into and out of printing relation with the latter, latch disc means associated with said one cylinder, a latch member engageable with said latch disc means, first spring means for said latch member for normally disposing the latter in an operative position to be engaged by said latch disc means, second spring means for urging said latch disc means in a direction to move said one cylinder away from said other cylinder and engaging said latch disc means with said latch member in the normal operative position of the latter to hold said one cylinder in printing relation with said other cylinderpcam means for said latch disc means for relieving the latter from said latch member against the force of said second spring means, trip means for said latch memher for disposing the same in an inoperative position free of said latch disc means, and sheet detector means associated with said trip means including a feeler finger pivotally mounted above .the path of travel of sheets being fed to said printing couple for movement toward and away from said path, said feeler finger in the absence of a sheet therebelow being operable in predetermined timed sequence with operation of said cam means for movement toward said trip means to eil'ect actuation thereof to dispose said latch member in its inoperative position.

5. A printing press inclvding a printing couple comprising a pair of printing cylinders one of which is movable toward and away from the other into and out of printing relation with the latter, latch disc means associated with said one cylinder, a latch member engageable with said latch disc means, first spring means for said latch member for normally disposing the latter in an operative position to be engaged by said latch disc means, second spring means for urging said latch disc means in a direction to move said one cvlinder away from said'otl er cylinder and engaging said latch disc means with said latch member in the normal operative position of the latter to hold said one cylinder in printing relation with said other cylinder. cam means for said latch disc means for relieving the latter from said latch member against the force of said second spring means. trip means for said latch member for disposing the same in an inoperative position free of said lat-ch disc means, and sheet detector means associated with said last named means including a feeler finger pivotally mounted above the path of travel of sheets being fed to said printing couple for movement toward and away from said path, said feeler finger in the absence of a sheet therebelow being operable in predetermined timed sequence with operation of WILLIAM WARD DAVIDSON.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 333,879 Maxson Jan. 5, 1886 530,310 Sears Dec. 4, 1894 711,147 Allen Oct. 14, 1902 i Number 18 Name Date Scott June 26, 1906 Sturtevant May 21, 1912 Elsworth June 17, 1913 Hermann Mar. 31, 1914 Parker Mar. 16, 1915 Trundle Aug. 3, 1915 Sheldon Sept. 4, 1923 Huebner Oct. 23, 1923 Redner Nov. 18, 1924 Smith Mar. 31, 1925 Chisholm et a1 Nov. 1, 1927 Slettevold Mar. 30, 1937 Peyrebrune Aug. 30, 1938 Brownsey July 11, 1939 Yeo Dec. 31, 1940 Davidson Jan. 20, 1942 

